Re: [PATCH] usb: mon: Change return type to vm_fault_t

[Greg KH]

On Mon, Apr 16, 2018 at 05:18:35PM +0530, Souptick Joarder wrote:
> On Mon, Apr 16, 2018 at 1:17 PM, Greg KH  wrote:
> > On Sun, Apr 15, 2018 at 04:10:08AM -0700, Matthew Wilcox wrote:
> >> On Sun, Apr 15, 2018 at 07:49:16AM +0200, Greg KH wrote:
> >> > On Sun, Apr 15, 2018 at 12:36:02AM +0530, Souptick Joarder wrote:
> >> > > Use new return type vm_fault_t for fault handler
> >> > > in struct vm_operations_struct.
> >> >
> >> > Why?
> >>
> >> commit 1c8f422059ae5da07db7406ab916203f9417e396
> >> Author: Souptick Joarder 
> >> Date:   Thu Apr 5 16:25:23 2018 -0700
> >>
> >> mm: change return type to vm_fault_t
> >>
> >> The plan for these patches is to introduce the typedef, initially just
> >> as documentation ("These functions should return a VM_FAULT_ status").
> >> We'll trickle the patches to individual drivers/filesystems in through
> >> the maintainers, as far as possible.  Then we'll change the typedef to
> >> an unsigned int and break the compilation of any unconverted
> >> drivers/filesystems.
> >>
> >> vmf_insert_page(), vmf_insert_mixed() and vmf_insert_pfn() are three
> >> newly added functions.  The various drivers/filesystems where return
> >> value of fault(), huge_fault(), page_mkwrite() and pfn_mkwrite() get
> >> converted, will need them.  These functions will return correct
> >> VM_FAULT_ code based on err value.
> >>
> >> We've had bugs before where drivers returned -EFOO.  And we have this
> >> silly inefficiency where vm_insert_xxx() return an errno which (afaict)
> >> every driver then converts into a VM_FAULT code.  In many cases drivers
> >> failed to return correct VM_FAULT code value despite of vm_insert_xxx()
> >> fails.  We have indentified and clean up all those existing bugs and
> >> silly inefficiencies in driver/filesystems by adding these three new
> >> inline wrappers.  As mentioned above, we will trickle those patches to
> >> individual drivers/filesystems in through maintainers after these three
> >> wrapper functions are merged.
> >
> > Then put a summary of this type of thing in the original patch please!
> 
> Ok, I will add it in change log and send v2.
> >
> > When a maintainer gets a patch with no context at all, the first
> > reaction is to just reject it (especially as many of these patches were
> > sent privately and did not go on any public mailing list, those all got
> > automatically dropped...)
> 
> For few drivers only maintainers name is mentioned without any mailing list
> in Maintainer file. Not sure which mailing list to add for the same.

get_maintainers.pl will always tell you a mailing list to cc: for any
file/patch.

thanks,

greg k-h
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Re: [PATCH] usb: mon: Change return type to vm_fault_t

[Matthew Wilcox]

On Mon, Apr 16, 2018 at 05:18:35PM +0530, Souptick Joarder wrote:
> On Mon, Apr 16, 2018 at 1:17 PM, Greg KH  wrote:
> > When a maintainer gets a patch with no context at all, the first
> > reaction is to just reject it (especially as many of these patches were
> > sent privately and did not go on any public mailing list, those all got
> > automatically dropped...)
> 
> For few drivers only maintainers name is mentioned without any mailing list
> in Maintainer file. Not sure which mailing list to add for the same.

I thought you were using scripts/get_maintainer.pl to get the maintainers;
I didn't realise you were going through MAINTAINERS manually.
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Re: [PATCH] usb: mon: Change return type to vm_fault_t

[Souptick Joarder]

On Mon, Apr 16, 2018 at 1:17 PM, Greg KH  wrote:
> On Sun, Apr 15, 2018 at 04:10:08AM -0700, Matthew Wilcox wrote:
>> On Sun, Apr 15, 2018 at 07:49:16AM +0200, Greg KH wrote:
>> > On Sun, Apr 15, 2018 at 12:36:02AM +0530, Souptick Joarder wrote:
>> > > Use new return type vm_fault_t for fault handler
>> > > in struct vm_operations_struct.
>> >
>> > Why?
>>
>> commit 1c8f422059ae5da07db7406ab916203f9417e396
>> Author: Souptick Joarder 
>> Date:   Thu Apr 5 16:25:23 2018 -0700
>>
>> mm: change return type to vm_fault_t
>>
>> The plan for these patches is to introduce the typedef, initially just
>> as documentation ("These functions should return a VM_FAULT_ status").
>> We'll trickle the patches to individual drivers/filesystems in through
>> the maintainers, as far as possible.  Then we'll change the typedef to
>> an unsigned int and break the compilation of any unconverted
>> drivers/filesystems.
>>
>> vmf_insert_page(), vmf_insert_mixed() and vmf_insert_pfn() are three
>> newly added functions.  The various drivers/filesystems where return
>> value of fault(), huge_fault(), page_mkwrite() and pfn_mkwrite() get
>> converted, will need them.  These functions will return correct
>> VM_FAULT_ code based on err value.
>>
>> We've had bugs before where drivers returned -EFOO.  And we have this
>> silly inefficiency where vm_insert_xxx() return an errno which (afaict)
>> every driver then converts into a VM_FAULT code.  In many cases drivers
>> failed to return correct VM_FAULT code value despite of vm_insert_xxx()
>> fails.  We have indentified and clean up all those existing bugs and
>> silly inefficiencies in driver/filesystems by adding these three new
>> inline wrappers.  As mentioned above, we will trickle those patches to
>> individual drivers/filesystems in through maintainers after these three
>> wrapper functions are merged.
>
> Then put a summary of this type of thing in the original patch please!

Ok, I will add it in change log and send v2.
>
> When a maintainer gets a patch with no context at all, the first
> reaction is to just reject it (especially as many of these patches were
> sent privately and did not go on any public mailing list, those all got
> automatically dropped...)

For few drivers only maintainers name is mentioned without any mailing list
in Maintainer file. Not sure which mailing list to add for the same.
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Re: [PATCH] usb: mon: Change return type to vm_fault_t

[Greg KH]

On Sun, Apr 15, 2018 at 04:10:08AM -0700, Matthew Wilcox wrote:
> On Sun, Apr 15, 2018 at 07:49:16AM +0200, Greg KH wrote:
> > On Sun, Apr 15, 2018 at 12:36:02AM +0530, Souptick Joarder wrote:
> > > Use new return type vm_fault_t for fault handler
> > > in struct vm_operations_struct.
> > 
> > Why?
> 
> commit 1c8f422059ae5da07db7406ab916203f9417e396
> Author: Souptick Joarder 
> Date:   Thu Apr 5 16:25:23 2018 -0700
> 
> mm: change return type to vm_fault_t
> 
> The plan for these patches is to introduce the typedef, initially just
> as documentation ("These functions should return a VM_FAULT_ status").
> We'll trickle the patches to individual drivers/filesystems in through
> the maintainers, as far as possible.  Then we'll change the typedef to
> an unsigned int and break the compilation of any unconverted
> drivers/filesystems.
> 
> vmf_insert_page(), vmf_insert_mixed() and vmf_insert_pfn() are three
> newly added functions.  The various drivers/filesystems where return
> value of fault(), huge_fault(), page_mkwrite() and pfn_mkwrite() get
> converted, will need them.  These functions will return correct
> VM_FAULT_ code based on err value.
> 
> We've had bugs before where drivers returned -EFOO.  And we have this
> silly inefficiency where vm_insert_xxx() return an errno which (afaict)
> every driver then converts into a VM_FAULT code.  In many cases drivers
> failed to return correct VM_FAULT code value despite of vm_insert_xxx()
> fails.  We have indentified and clean up all those existing bugs and
> silly inefficiencies in driver/filesystems by adding these three new
> inline wrappers.  As mentioned above, we will trickle those patches to
> individual drivers/filesystems in through maintainers after these three
> wrapper functions are merged.

Then put a summary of this type of thing in the original patch please!

When a maintainer gets a patch with no context at all, the first
reaction is to just reject it (especially as many of these patches were
sent privately and did not go on any public mailing list, those all got
automatically dropped...)  Make it trivial for a reviewer to understand
what the patch is for and why it needs to be applied.

thanks,

greg k-h
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Re: [PATCH] usb: mon: Change return type to vm_fault_t

[Matthew Wilcox]

On Sun, Apr 15, 2018 at 07:49:16AM +0200, Greg KH wrote:
> On Sun, Apr 15, 2018 at 12:36:02AM +0530, Souptick Joarder wrote:
> > Use new return type vm_fault_t for fault handler
> > in struct vm_operations_struct.
> 
> Why?

commit 1c8f422059ae5da07db7406ab916203f9417e396
Author: Souptick Joarder 
Date:   Thu Apr 5 16:25:23 2018 -0700

mm: change return type to vm_fault_t

The plan for these patches is to introduce the typedef, initially just
as documentation ("These functions should return a VM_FAULT_ status").
We'll trickle the patches to individual drivers/filesystems in through
the maintainers, as far as possible.  Then we'll change the typedef to
an unsigned int and break the compilation of any unconverted
drivers/filesystems.

vmf_insert_page(), vmf_insert_mixed() and vmf_insert_pfn() are three
newly added functions.  The various drivers/filesystems where return
value of fault(), huge_fault(), page_mkwrite() and pfn_mkwrite() get
converted, will need them.  These functions will return correct
VM_FAULT_ code based on err value.

We've had bugs before where drivers returned -EFOO.  And we have this
silly inefficiency where vm_insert_xxx() return an errno which (afaict)
every driver then converts into a VM_FAULT code.  In many cases drivers
failed to return correct VM_FAULT code value despite of vm_insert_xxx()
fails.  We have indentified and clean up all those existing bugs and
silly inefficiencies in driver/filesystems by adding these three new
inline wrappers.  As mentioned above, we will trickle those patches to
individual drivers/filesystems in through maintainers after these three
wrapper functions are merged.

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Re: [PATCH] usb: mon: Change return type to vm_fault_t

[Greg KH]

On Sun, Apr 15, 2018 at 12:36:02AM +0530, Souptick Joarder wrote:
> Use new return type vm_fault_t for fault handler
> in struct vm_operations_struct.

Why?

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